Water based paint, and thinning it down.

[ericmark]

We used to use oil based paint on wood, but the drying time was a real problem, it would seem dry after two weeks, but try moving the benches etc, and we still got paint on our hands, clearly where some bit was a bit thicker than it should have been, so there was always a worry putting benches out too early.

So we did a trial, and replaced the wood with plastic, so no painting required, but plastic sags in time so had angle iron under the plastic to stop sagging, so whole process was very time-consuming, but hopefully they will now last 25 years.

But our new leader decided on water based paint, not as much gloss, but totally dry by the next day, it says add water to the paint when on bare wood, then subsequent coats undiluted.

Sounds good in theory, but having mixed a kettle of paint and water, the question is what to do with remaining paint? And with hot weather, it is by end of the kettle nearly back to pre-diluted anyway. So it is tempting to start using it for the second coat, however this tends to cause the paint to wrinkle. Leave it and the wrinkles go, but then left with bits without paint, lucky where it happened it was not critical, but it seems water based paint needs different treatment, but I am new to water based, so what treatment does it need?

 

[Wayners]

Waterbased paint it's good practice to just dilute what you are going to use that day.
When paint comes out the can you never pour unused paint back in because of contamination.
To dilute small quantities use kitchen scales to work out the percentage of water needed.
Bathroom scales for larger amounts.
Veg bags are 30p from supermarkets like Tesco and you can use them to strain paint.
You can just push net in kettle pushing bits down is a hack.
As for storing paint you want as little air as possible in can so I used to keep 2.5lt cans or 1lt plastic lidded pots to store paint.

 

[thomasfrank]

We used to use oil based paint on wood, but the drying time was a real problem, it would seem dry after two weeks, but try moving the FNF benches etc, and we still got paint on our hands, clearly where some bit was a bit thicker than it should have been, so there was always a worry putting benches out too early.

So we did a trial, and replaced the wood with plastic, so no painting required, but plastic sags in time so had angle iron under the plastic to stop sagging, so whole process was very time-consuming, but hopefully they will now last 25 years.

But our new leader decided on water based paint, not as much gloss, but totally dry by the next day, it says add water to the paint when on bare wood, then subsequent coats undiluted.

Sounds good in theory, but having mixed a kettle of paint and water, the question is what to do with remaining paint? And with hot weather, it is by end of the kettle nearly back to pre-diluted anyway. So it is tempting to start using it for the second coat, however this tends to cause the paint to wrinkle. Leave it and the wrinkles go, but then left with bits without paint, lucky where it happened it was not critical, but it seems water based paint needs different treatment, but I am new to water based, so what treatment does it need?

You can follow the tin’s instructions and keep the diluted paint for the first coat only. Don’t use partially dried diluted paint for the second coat; the altered water ratio can cause wrinkling. In hot weather, mix smaller batches and keep the container covered.